Simplify: centralize paths in layout, dedup zfs snapshot refs, remove dead code

- Add layout.Config methods (ReleasesDir, PostReceiveHookPath, RCScriptPath,
  RCConfPath) so main.go and jailmgr no longer hand-build paths that layout
  already owns.
- Extract zfsutil.snapRef to replace three inline dataset@tag Sprintfs.
- Remove seven unused exported functions (zfsutil.Exists, jailmgr.Stop,
  sh.RunWithStdinFile, and four dead layout.Config path methods) and their
  now-unused imports.

1 files changed, 5 insertions, 7 deletions

diff --git a/internal/zfsutil/zfsutil.go b/internal/zfsutil/zfsutil.go
index 3d3bd40..8f1b0e2 100644
--- a/internal/zfsutil/zfsutil.go
+++ b/internal/zfsutil/zfsutil.go
@@ -11,20 +11,18 @@ import (
 	"skiff/internal/sh"
 )
 
-func Exists(ctx context.Context, dataset string) bool {
-	_, err := sh.Output(ctx, "", "zfs", "list", "-H", "-o", "name", dataset)
-	return err == nil
+func snapRef(dataset, tag string) string {
+	return fmt.Sprintf("%s@%s", dataset, tag)
 }
 
 // Clone creates a new dataset from a (read-only) snapshot of base, mounted
 // at mountpoint. base must already have a snapshot named baseSnapshot.
 func Clone(ctx context.Context, out io.Writer, base, baseSnapshot, dataset, mountpoint string) error {
-	src := fmt.Sprintf("%s@%s", base, baseSnapshot)
-	return sh.Run(ctx, out, "", "zfs", "clone", "-o", "mountpoint="+mountpoint, src, dataset)
+	return sh.Run(ctx, out, "", "zfs", "clone", "-o", "mountpoint="+mountpoint, snapRef(base, baseSnapshot), dataset)
 }
 
 func Snapshot(ctx context.Context, out io.Writer, dataset, tag string) error {
-	return sh.Run(ctx, out, "", "zfs", "snapshot", fmt.Sprintf("%s@%s", dataset, tag))
+	return sh.Run(ctx, out, "", "zfs", "snapshot", snapRef(dataset, tag))
 }
 
 // Rollback discards everything written to dataset since the snapshot named
@@ -32,7 +30,7 @@ func Snapshot(ctx context.Context, out io.Writer, dataset, tag string) error {
 // used both for the automatic post-health-check-failure rollback and for a
 // manual `skiff rollback` days later.
 func Rollback(ctx context.Context, out io.Writer, dataset, tag string) error {
-	return sh.Run(ctx, out, "", "zfs", "rollback", "-r", fmt.Sprintf("%s@%s", dataset, tag))
+	return sh.Run(ctx, out, "", "zfs", "rollback", "-r", snapRef(dataset, tag))
 }
 
 // Snapshots lists snapshot names (without the dataset@ prefix), newest last.